1. Field of the Invention
The present invention relates generally to display of Web pages and, more particularly, to assembly and update of Web page elements.
2. Description of the Related Art
The Internet is a computer network that provides access to the World Wide Web (“the Web”), a vast collection of pages comprised of text, graphical, and multimedia elements. Graphical user interface programs called Web browsers are employed by Internet users to receive, or download, the Web pages from servers and display the pages at their client computers. A Web browser displays Web pages by showing the text and graphical elements on a client display screen and by playing sound files and showing video sequences.
The rapid increase in the number of Internet users and in the amount of information being downloaded by users has resulted in high volumes of traffic, as well as increasing delays in downloading Web pages. Delays in downloading pages make an Internet user's browsing experience less enjoyable. This is especially true for Internet users who do not have high-speed access to the Internet. The response time for the transfer of page elements between servers and clients could be improved if the amount of data traffic passing over the Internet could be reduced.
To download a Web page, a user at a client machine requests a Web page by sending a Web page address to the corresponding Web server. A Web page address is specified by a uniform resource locator (URL). When the Web server receives the URL request from a client machine, it determines the format and elements of the requested Web page and constructs a text file according to the hypertext mark-up language (HTML) standard. The HTML file specifies the text to be written and the Web page elements, such as URLs for image files that are to be viewed or displayed, and the format in which they should be presented. The server sends the HTML text file to the client machine, along with any corresponding data files specified by the HTML code.
At the client machine, the user's Internet browser receives the HTML code and automatically renders the page elements, displaying the text data and sending further requests for files specified by URLs in the HTML code. The requests for files may include, for example, image files at servers other than the server from which the original HTML code was received. Thus, it should be apparent that displaying a single Web page may involve many different requests for data and numerous transfers of data between the client machine and one or more Web servers.
One contributor to the excessive Internet traffic that is slowing down the Web is the requirement for reloading of Web pages. Typically, each time a user “visits” a Web page by requesting its contents, that user's Web browser must reload the page data by requesting the entire HTML code and the corresponding data elements. Although some Web pages have a large number of elements that change frequently, it is more typical for a page to be largely static. That is, most of the page elements will not change. The download of Web pages could proceed much more smoothly if all of the elements of a Web page did not need to be transferred from a server every time the page is requested.
Some Web page source files can be specified in the HTML code, such as graphical images and sound files, so they can be referenced by name and independently requested from corresponding servers. The graphical image files are typically among the largest elements of a Web page and take the most time to download. Thus, browsers may cache such files at the user's computer. When a user requests a Web page, the user's browser can check for updated graphical image files. If there has been no change between the version stored in the user's cache and the version to be obtained from the Web server, then the browser will not request the server version, and instead will use the cached version. This reduces the number of page elements that must be requested from the Internet, giving the user the appearance of a faster connection, and thereby providing a more pleasurable experience.
Other developments illustrate the great effort at reducing the amount of data that must be transferred between user (client) computers and the Web servers from which page elements are retrieved. For example, companies have begun to provide a Web cache service whereby they provide intermediate storage of data files at a network location between the Web server and the user computer. The intermediate storage is typically distributed about in multiple network locations to provide faster response to user requests for graphical images. Web cache services work in concert with Web page servers, as follows. When users request a page from a Web server, the Web server assembles the page elements into the HTML file that will be sent to the user browser. The Web server determines which Web server or cache location can most quickly provide a graphical element of the requested page. The Web server places the corresponding URL in the HTML code that is sent to the user's computer. When the user's browser receives the HTML code, it displays the HTML text and requests the graphical elements from the servers indicated by the Web server. In this way, users should receive page elements more quickly than if all the elements came from the original Web server.
While such Web cache techniques can deliver graphical images more quickly to users, the cache files are limited to “tagged” files, such as graphical images (JPEG, GIF, and other image files) and sound files (such as WAV files). The HTML files, and therefore the portions of the Web page that comprise text, must still be obtained from the original server. Moreover, with every page request, all of the page elements will be requested, even if there have been no changes in the individual elements.
There presently is no way to independently request download of individual elements from a Web page, other than tagged elements. Thus, every time a page reload or refresh operation is initiated by the user, the entire contents of the Web page will be requested from a server, the lone exception being any tagged element files that are cached at the user's computer. It would reduce the amount of data to be transferred between client and server if refresh requests could be processed by delivering only the updated portions of a Web page, and if such independent updates could include elements that are not tagged files, such as Web page text portions.
Another development that reduces data transfer for display of Web pages is the use of applets written in the “Java” programming language, as developed by Sun Microsystems, Inc. of Mountain View, Calif., USA. Such applets are files of executable code that are received at user client machines from Web servers and then executed at the client. Thus, the Java applets comprise computer programs that must be received from a server and then must be executed from within a suitably equipped (Java-enabled) browser.
A browser typically “pauses” in its page display operations while a Java applet is being downloaded. Once they are executing, Java applets give the user the illusion of dynamic (and continuous) downloading activities. That is, to generate an equivalent Web page display without the Java applet, the user would have to continuously download data from a Web server. The Java applet may provide dynamic display of information in the user's Web browser, but cannot access additional resources on the user computer, and must be fully downloaded before they can execute their operations. Moreover, the information displayed by a Java applet cannot be updated independently of the applet itself. Thus, to update the Java display, the user must download another version of the Java applet. In addition, each time the display is changed, a new applet must be written and provided at the Web server.
From the discussion above, it should be apparent that there is a need for a quick, efficient means of assembling Web pages for display, to include text elements received from discrete network locations, and there is a need for independent update of individual elements of a Web page without reassembling the entire Web page. The present invention fulfills this need.